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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 50 |
| 6 | 144 |
| 7 | 1078 |
| 8 | 7936 |
| 9 | 66096 |
| 10 | 611200 |
| 11 | 6248682 |
| 12 | 69926976 |
| 13 | 850848414 |
| 14 | 11187719984 |
| 15 | 158122436400 |
| 16 | 2390945284096 |
| 17 | 38518483536706 |
| 18 | 658706393035152 |
| 19 | 11918123304961222 |
| 20 | 227474585229393600 |
| 21 | 4567806759318652080 |
[0,0,0,0,50,144,1078,7936,66096,611200,6248682, 69926976,850848414,11187719984,158122436400, 2390945284096,38518483536706,658706393035152, 11918123304961222,227474585229393600, 4567806759318652080] |